Andy Murray's mood ahead of his semi-final in the ATP World Tour Finals tomorrow seems, on the face of it, to change with the ebbing tide of the nearby Thames.

The music that accompanied his impressive win over David Ferrer at the O2 Arena in Greenwich last night could not have been more appropriate: Unchain Your Heart.

On court, it looked as if Murray had done just that. He started nervously, then played with a freedom that blew the world No7 away, giving up only four games.

Victory not only put him in sight of a possible match with Rafael Nadal, but lifted him from No5 back to No4 in the ATP rankings, ahead of the man he beat on Sunday, Robin Soderling. Murray punched the air and smiled like a kid at Christmas. The packed arena roared their support.

Yet, an hour later, his demeanour had darkened. He did not expect to beat Nadal if they met in the semis because the Mallorcan is "obviously the best player in the world", he said. "I've watched his matches here. He's been playing unbelievably well. You know, I don't seem to beat those guys in the big matches."

This sounded like a dig at the media, who had quite fairly criticised him for his poor match against Roger Federer on Tuesday and wondered why he could not produce the outstanding tennis that had accounted for Soderling.

Murray also rankled when he was asked whether he had expected more from his year after such a good 2009, and if he could get back to No3 (which he might do if he wins this tournament), or better.

"Every year I want to try and improve," he said. "But I don't know how many times I need to keep saying it: I'm playing with the two best players of all time in front of me. So it's a very, very difficult thing to do. I've managed it once. I haven't finished a year there yet, but I've managed to get to No2, which was a great achievement. I'd love to try and get to No1. That's what I'm working towards. I'm working as hard as I can to try and get there. I hope next year I can finish higher."

The problem for Murray – as it is for everyone in the top 10 – is the roadblock in front of him, and his time in tennis history. Federer is not quite ready to leave the scene, Nadal is there for as long as his knees hold up.

But Murray does not want them to go. He wants to beat them on their own terms and be a legitimate No1. He cannot understand why other people do not get it.

So, when he says he is not confident of beating Nadal or Federer, he is playing mind games with his critics and, ultimately, with himself. The truth is, he has to believe he can beat them every time or there is not much point playing the game, not much point pretending he is a contender.

A mean time in Greenwich

The tournament, clearly, has been a huge success again, with full houses nearly every session in a venue that has long since stopped being a folly. The Dome is home.

The facilities and the setting are brilliant, as is much of the tennis, of course. But the ATP may yet move it away from London when the current deal ends in 2013. That would be a shame. It has moved about all over the world and is in its second year here. If the ATP want to make it an even bigger end-of-season shindig than it already is, they should leave well alone for at least another five years.